U.S. Pat. No. 4,750,590 to Otala shows an open-loop elevator control system with solenoid actuated guide shoes. The disclosure suggests using the concept of first ascertaining the out-of-straightness of the guide rails for storage in a computer memory and subsequently controlling the guide shoes by recalling the corresponding information from memory and correcting the guide rail shoe positions accordingly.
Kokai 3-51281 of Kagami is similar to Otala except is additionally concerned with a supposed variable stiffness of the rails along with an eccentric load causing difficulties in truly learning the rail. See also Kokai 3-23185, 3-51280 and 3-115076 for similar disclosures. Kokai 3-124683 shows apparatus for measuring the mounting accuracy of a guide rail by sensing the position of the car relative to a piano wire and a rail.
Kokai 60-36279 discloses an electromagnet guide in a closed loop control based on position and current feedback. The text that explains FIG. 8 seems to suggest memorizing rail displacement error.
U.S. Pat. No. 4,754,849 to Ando and Kokai 58-39753 show electromagnet guides using a vertical wire as a positional reference.
U.S. Pat. No. 5,027,925 shows a procedure for damping the vibrations of an elevator car supported by elastic suspension elements and controlling a vibration damper in parallel with the elastic suspension elements with the output of an acceleration sensor. See also Kokai 61-22675 for a disclosure of variable coulomb-damping in parallel to the car top hitch springs which carry the rope loads suspending the crosshead. See also Kokai 60-15374 for a similar device for controlling vertical vibrations using an accelerometer in FIG. 11. Various other patent documents disclose acceleration-based, closed-loop "active" suspensions for automobiles, railroad cars, military tanks, etc. See, e.g., U.S. Pat. Nos. 4,809,179; 4,892,328 and 4,898,257. Similarly, a real time simulation was used to analyze two idealized MAGLEV suspensions: an attraction (ferromagnetic) system and a repulsion (cryogenic) system in "Performance of Magnetic Suspension for High-speed Vehicles" by C. A. Skalski, published in the June 1974 Journal of Dynamic Systems Measurement and Control. FIG. 8 thereof shows an accelerometer connected to an integrator.
An active horizontal suspension is disclosed in United Kingdom Patent Application GB 2 238 404 A, having pressure applied to the guide rails sensed at a stop and maintained constant at the stopped value by driving actuable guides in a feedback loop with the outputs of a pressure or displacement sensor.